1. Field of the Invention
The present invention relates to an ink jet service station. More specifically, the present invention discloses an ink jet cap in an ink jet service station.
2. Description of the Prior Art
Ink jet printing systems are found in a variety of faxes, printers, photostats and other types of office equipment. To ensure the continuous proper operation of an ink jet print head within the ink jet printing system, the ink jet printing system has an ink jet service station. The ink jet service station performs basic head cleaning and capping functions. Prior to printing, and at periodic intervals during a printing session, the ink jet print head is wiped clean to ensure its performance. A wiper in the ink jet service station performs this wiping function. The ink jet print head is capped when the printing system is not in use. An ink jet capping system performs this capping function within the ink jet service station.
An ink jet print head comprises a plurality of nozzles. These nozzles spray the ink onto a media, such as paper, to perform the printing operation. The ink jet print head is capped during periods of inactivity to prevent the ink inside these nozzles from drying out, which would otherwise clog the nozzles. Within the nozzles are heating elements. These heating elements heat the ink prior to it being jetted onto the media. This heating operation reduces the viscosity of the ink, and is also responsible for the actual jetting of the ink.
To cap the ink jet print head, the ink jet print head enters the ink jet service station and the cap, which is generally just an open-ended box of rubber, is lifted up to the ink jet print head. The lips of the cap seal quite readily with the ink jet print head, and overpressure develops within the cap as the mouth of the cap is pressed onto the ink jet print head. This overpressure results in backflow of the ink within the nozzles. Consequently, the heating elements within the nozzles have no ink upon which to act when a printing operation begins. This causes the heating elements to overheat, which can lead to damage to the nozzles.
It is therefore a primary objective of this invention to provide a capping system for an ink jet service station that prevents overpressure within the cap when capping the ink jet print head.
The capping system, briefly summarized, is used to cap an ink jet print head, and has a cap for capping the ink jet print head, and a supporting structure for mechanically engaging or disengaging the cap with the ink jet print head. The cap has a vent. When the supporting structure engages the cap with the ink jet print head, the cap covers the ink jet print head to cap the ink jet print head. The vent in the cap ensures that the pressure inside the volume of the cap equalizes with the pressure outside the volume of the cap. This prevents overpressure within the cap.
It is an advantage of the present invention that by preventing overpressure within the cap when capping the ink jet print head, the present invention prevents backflow of ink within the nozzles of the ink jet print head. Consequently, the heating elements within the nozzles do not overheat for lack of ink, and the useful lifetime of the ink jet print head is thus extended.
This and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment, which is illustrated in the various figures and drawings.